Interpretive Summary: The USDA GEM (Germplasm Enhancement of Maize) project is a
cooperative effort to facilitate the introduction of exotic maize
germplasm into US breeding programs. We report here 20 superior F2S2 families containing 50%-tropical germplasm by pedigree. These lines yielded well in the southern corn growing regions of the US in comparison to commercial check hybrids, and also performed well by several other criteria .

Technical Abstract:
The USDA GEM (Germplasm Enhancement of Maize) project is a
cooperative effort to facilitate the introduction of exotic maize
germplasm into US breeding programs. We report here 20 superior F2S2 families containing 50%-tropical germplasm by pedigree. These lines yielded well in the southern corn growing regions of the US in comparison to commercial check hybrids, and also performed well by several other criteria .